Moreover, other cage-type structure systems such as R\(_5\) Rh\(_6\) Sn\(_{18}\)  (R = Sc, Lu and Y) and Pr-based heavy-fermion filled skutterudite (Pr,La)(Ru,Os)\(_4\) Sb\(_{12}\) , PrPt\(_4\) Ge\(_{12}\)  are among the few compounds which show time-reversal symmetry breaking (TRSB) in their superconducting state with multi-gap features [1]}, [2]}, [3]}, [4]}, [5]}, [6]}. This further motivates a detailed study of the symmetry-properties of pairing in the quasi-skutterudite Lu\(_3\) Os\(_4\) Ge\(_{13}\) , which exhibits another analogous cage-type structure with multi-gap superconductivity and structural complexity.
